This invention relates to a device for plasmapheresis by centrifugation.
Several devices are known and commercially available which enable separation--called plasmapheresis--of plasma from red cells contained in the blood drawn from a donor or a patient in order to remove the plasma alone and re-introduce the red cells; with such prior devices, said separation is accomplished by centrifugating the blood, putting to use the different specific gravities of plasma and red cells, and it will be appreciated that of fundamental import is the dynamic balancing of the rotor which includes the ducting wherethrough blood is flown for undergoing centrifugation.
With some prior devices, this dynamic balance is obtained by suitably arranging counterweights at opposed positions to swellings in the ducts intended for accommodating the blood, but it will be appreciated that, if the system is balanced with all the ducts filled, it would not be so at the start of the operation, before the blood reaches it, unless said swellings are filled with physiological solution. This filling operation, which is inherently complicated because it involves preliminary removal of the air contained therein, represents a significant portion of the overall time duration of the operation, especially where this is performed on a donor, and is accordingly a highly disadvantageous feature of the devices.
Conventional devices, moreover, tend to be quite expensive owing to the complexity of their components, and generally unreliable in operation.